java - ZuulFallbackProvider 没有被调用

Question

如果 Zuul 找不到服务，我会尝试进行后备。我有一个 ZuulSever，代码如下:

@SpringBootApplication
@EnableZuulProxy
@EnableDiscoveryClient
public class ZuulServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ZuulServerApplication.class, args);
    }

    @Bean
    public ZuulFallbackProvider fallBackProvider() {
        return new ZuulFallbackProvider() {

            @Override
            public ClientHttpResponse fallbackResponse() {

                return new ClientHttpResponse() {
                    @Override
                    public HttpHeaders getHeaders() {
                        return null;
                    }
                    @Override
                    public InputStream getBody() throws IOException {
                        return new ByteArrayInputStream("Hello".getBytes());
                    }

                    @Override
                    public String getStatusText() throws IOException {
                        // TODO Auto-generated method stub
                        return "Service Down";
                    }

                    @Override
                    public HttpStatus getStatusCode() throws IOException {
                        // TODO Auto-generated method stub
                        return HttpStatus.OK;
                    }

                    @Override
                    public int getRawStatusCode() throws IOException {
                        // TODO Auto-generated method stub
                        return 200;
                    }

                    @Override
                    public void close() {
                        // TODO Auto-generated method stub

                    }
                };
            }

            @Override
            public String getRoute() {
                // TODO Auto-generated method stub
                return "*";
            }

        };
    }
}

当我的 route 的服务启动并运行时，我能够获得输出。但是，当我关闭路由中的服务时，我预计回退会启动。但我仍然看到一条错误消息，而不是回退消息。为什么没有调用后备？我正在使用 Dalston Release 版本。

Answer 1

如果您将 Zuul 配置为直接连接到路由的 URL，它将使用 SimpleHostRoutingFilter，在发生错误时(几乎)总是返回 500。任何 FallbackProvider 都不会启动。

我使用了自定义的 SimpleHostRoutingFilter 来代替:

public class CustomErrorHostRoutingFilter extends SimpleHostRoutingFilter {
    public CustomErrorHostRoutingFilter(ProxyRequestHelper helper, ZuulProperties properties, ApacheHttpClientConnectionManagerFactory connectionManagerFactory, ApacheHttpClientFactory httpClientFactory) {
        super(helper, properties, connectionManagerFactory, httpClientFactory);
    }

    @Override
    protected ZuulException handleException(Exception ex) {
        if (ex instanceof ConnectTimeoutException) {
            return new ZuulException(ex, "Downstream timeout", HttpServletResponse.SC_GATEWAY_TIMEOUT, ex.getMessage());
        }

        if (ex instanceof IOException) {
            return new ZuulException(ex, "Downstream I/O error", HttpServletResponse.SC_SERVICE_UNAVAILABLE, ex.getMessage());
        }

        return super.handleException(ex);
    }
}

还需要某种配置类:

@Configuration
@EnableZuulProxy
public class ZuulConfiguration {

    @Bean
    public SimpleHostRoutingFilter simpleHostRoutingFilter(ProxyRequestHelper helper,
                                                           ZuulProperties zuulProperties,
                                                           ApacheHttpClientConnectionManagerFactory connectionManagerFactory,
                                                           ApacheHttpClientFactory httpClientFactory) {
        return new CustomErrorHostRoutingFilter(helper, zuulProperties, connectionManagerFactory, httpClientFactory);
    }
}